1. Technical Field
The present disclosure relates to a wavelength converter, a wavelength converting device, a solid state laser device, and a laser system.
2. Related Art
Excimer lasers, that are typical ultraviolet light sources used in semiconductor lithography processes, may include KrF excimer lasers having a wavelength of approximately 248 nm, and ArF excimer lasers having a wavelength of approximately 193 nm.
Most ArF excimer lasers may be supplied to the market as two-stage laser systems including an oscillation stage laser and an amplification stage. A description will be given of a main configuration common to the oscillation stage laser and the amplification stage of the two-stage ArF excimer laser system. The oscillation stage laser may include a first chamber, and the amplification stage may include a second chamber. The insides of the first and second chambers may be filled with laser gas (mixture gas of F2, Ar, Ne, and Xe). The oscillation stage laser and the amplification stage may further include a power supply to supply electrical energy for exciting the laser gas. The oscillation stage laser and the amplification stage may each include the power supply, or the oscillation stage laser and the amplification stage may share a single power supply. First discharge electrodes, including a first anode and a first cathode respectively connected to the power supply, may be provided within the first chamber. Similarly, second discharge electrodes, including a second anode and a second cathode respectively connected to the power supply, may be provided within the second chamber.
The configuration unique to the oscillation stage laser may include, for example, a line-narrowing module. The line-narrowing module may typically include one grating, and at least one prism beam expander. A partial reflecting mirror and the grating may form an optical resonator, and the first chamber of the oscillation stage laser may be provided between the partial reflecting mirror and the grating.
When the electrical energy from the power supply is supplied to the first discharge electrodes and a discharge is generated between the first anode and the first cathode, the laser gas may be excited, and light may be generated when excitation energy is emitted. The light may be formed into laser light having the wavelength narrowed by the line-narrowing module, and the laser light may be output from the oscillation stage laser.
The two-stage laser system in which the amplification stage includes a resonator configuration may be referred to as a MOPO (Master Oscillator Power Oscillator), and the two-stage laser system in which the amplification stage includes no resonator configuration may be referred to as a MOPA (Master Oscillator Power Amplifier). When the laser light from the oscillation stage passes through the second chamber of the amplification stage, a control may be performed to generate a discharge between the second anode and the second cathode of the second discharge electrodes. Hence, the laser gas within the second chamber may be excited, and the laser light may be amplified and output from the amplification stage.
A related technique may be found in a U.S. Pat. No. 6,859,305, for example.